An estimated four million thick-billed murres nest in Nunavut, mostly on bird colonies such as this one on Coates Island. (CBC)Scientists in Nunavut and Newfoundland and Labrador are keeping a close watch on a species of seabirds known as thick-billed murres, which they say could provide clues about the health of the ocean waters around Canada.

An estimated four million thick-billed murres nest in Nunavut, but they have also been seen and harvested in Newfoundland and Labrador and in Greenland.

Scientists say they provide a good indication on the health of oceans, particularly how they're affected by a changing climate, sea ice conditions, development and the presence of contaminants such as mercury.

A research team, which includes members from Canadian universities and the Canadian Wildlife Service, attached geo-locating microchips to some thick-billed murres last year to record light and temperature conditions and to track the birds' movements.

Some surprising results

They are now catching the birds at several known colonies to get the devices back and download data from the microchips.

The information they've collected so far has produced some surprising details of how thick-billed murres move around the ocean, said Mark Mallory, a seabird biologist with the Canadian Wildlife Service in Iqaluit.

"What we're finding is the birds spend quite a bit longer in Hudson Bay than we thought, and they're moving through Hudson Strait much quicker than we thought," Mallory told CBC News.

"It kind of changes our perception on how the birds are moving, where they're moving and … what risks they're going to face at different times of the year."

Knowing where the birds are at any given time of the year is important in the event possible oil spills, development and changing water and climate conditions, said Bill Montevecchi, a research professor at Memorial University in St. John's, N.L.

"It looks like the males and females might be doing different things; birds from different colonies might be doing different things ... going to different wintering areas and using more of the ocean than we thought about," he said.

Diet continues to change

Mallory said the seabirds' diets continue to change, with more birds switching from their usual food source of Arctic cod to capelin.

Research has shown that capelin is not as nutritious as Arctic cod, and that could affect the growth of murre chicks.

The Canadian Wildlife Service is watching the effects of contaminants on the thick-billed murres. Traces of contaminants such as mercury have drifted into the Arctic ecosystem over the years, entering the food chain.

Mallory said the wildlife service's contaminants specialist recently flew to a thick-billed murre colony on Coates Island to collect some eggs and see whether there is mercury present.

"Mercury probably still is ... the hottest topic [in the contaminant world] … in the Arctic, because levels seem to be increasing," he said.